The present invention relates to linear power modules for actuating industrial tools and more particularly to a unit for increasing the power output of the module during a selected portion of its operating cycle.
Linear power modules typically have a power ram that is made to undergo reciprocating motion and that is connectable to the ram of an industrial tool for imparting linear motion to the tool ram in the operation of the tool. The linear power module includes a mechanism to effect the movement of the power ram. This mechanism usually takes the form of an air cylinder, a hydraulic cylinder, a spring mechanism, an explosive device, or an electromagnet apparatus. Industrial tools that require a very fast moving power ram, such as electrical terminal crimping tools, are generally limited to the use of explosive devices or spring mechanisms. These mechanisms, however, have the characteristic of relatively high power during the first part of the stroke of the power ram and a diminished amount of power as the stroke proceeds to its limit. Most industrial tool, such as terminal crimping tools, especially those having a linearly moving tool ram, require increased power during the last portion of the stroke. Therefore, the minimum power output of a linear power module determines its usefulness with respect to these industrial tools. An example of a linear power module and associated industrial tool having a linearly moving tool ram is shown in FIG. 1, and is the subject of copending patent application Ser. No. 08/xxxxxx, filed July xx, 1998, and is assigned to the present assignee. As seen in FIG. 1, an industrial terminal crimping tool 10 is positioned to be coupled to a linear power module 12. The tool 10 includes a frame 14 and a threaded portion 16 that is threaded into a hole in the frame. A tool ram 18 is slidable within a longitudinal hole in the threaded portion 16 toward an anvil 20. The threaded portion 16 is rigidly attached to a mounting flange 22 which removably attaches to the power module 12 via attachment bolts 24 in the usual manner. The power module 12 includes a compressible spring unit, not shown, that when compressed and then actuated, moves a power ram 26 that engages the tool ram 18 for operating the tool 10. A typical wire connector 30 is shown in FIG. 2 in a typical application. As shown, the wire connector 30 includes a C-shaped clamping member 32 and a wedge 34. The clamping member 32 has a web 36 and two oppositely formed rolled edges 38 that diverge from left to right, as viewed in FIG. 2. The rolled edges 38 form opposing channels for receiving a power cable 40, or wire, and a tap wire 42 with the wedge 34 therebetween. The wedge has opposite edges that diverge similarly to the rolled edges 38 and are concave to better seat the cylindrical shaped power cable 40 and tap wire 42. When installing the wire connector, the clamping member 32 is placed with one rolled edge over the power cable and the tap wire 42 in the opposite channel. The wedge 34 is then inserted into the larger end of the clamping member and forced into tight engagement with the cable 40, tap wire 42, and clamping member 32 and the assembly is then inserted into the tool 10 so that the edge of the clamping member 36 is against the anvil 20, as shown in FIG. 1, and the end of the wedge 34 is against the end of the tool ram 18. The tool 10 is then coupled to the power module 12 which is then actuated to drive the wedge 34 into full engagement with the clamping member to electrically interconnect the tap wire 42 to the cable 40 and produce the wire connection shown in FIG. 2.
It will be appreciated that the force, derived from the compressed spring unit, that the power ram exerts on the tool ram toward the end of its stroke is greatly reduced with respect to the force available at the beginning of its stroke. Therefore, the linear power module must be overly robust to be effective in operating the industrial tool. This, of course requires that the linear power module be made stronger and necessarily heavier to accommodate the additional stresses, making the device more cumbersome and less convenient to use as a portable unit.
What is needed is a linear power module having a power enhancing unit that is disposed between the power module and the industrial tool that provides a mechanical advantage so that the power ram exerts a diminished force on the tool ram in the beginning of its stroke and a greater force toward the end of the stroke when the increased force is most needed.
A linear power module for actuating a tool ram of an industrial tool includes a power ram arranged to undergo motion along a power axis. A power enhancing unit is disposed between the power unit and the industrial tool. The power enhancing unit includes a frame and an input member coupled to the power ram and arranged to undergo movement within the frame from a first position to a second position. The power ram is operable to exert a primary force on the input member to effect this movement. An output member is coupled to the tool ram and a power enhancing mechanism is coupled to both the input member and the output member and arranged so that upon movement of the input member the output member undergoes movement and exerts a secondary force on the tool ram that is greater than the primary force for a portion of the movement of the output member. The tool ram has a tool axis that is coaxial with the power axis.
An embodiment of the invention will now be described by way of example with reference to the following drawings.